Thermal transfer printing

Abstract

A thermal transfer printing sheet comprising a substrate having a coating comprising: (1) an anthraquinone dye of the formula: <CHEM> wherein each of R<1> and R<2>, independently, represents hydrogen or C1-4-alkyl and rings A and B are optionally substituted in the free positions by non-ionic groups, and (2) a monoazo dye of the formula: <CHEM> wherein each of R<3> and R<4>, independently, represents C1-4-alkyl optionally substituted by halogen, cyano, phenyl, C1-4-alkoxy, C1-4-alkoxycarbonyl, C1-4-alkylcarbonyloxy, R<6>CONH-, R<6>NHCO- or R<6>NHCOO- in which R<6> represents C1-4-alkyl or optionally substituted aryl; R<5> represents hydrogen, halogen, C1-4-alkyl, C1-4-alkoxy, C1-4-alkylthio, beta-cyanoethyl, C1-4-alkylcarbonylamino or C1-4-alkylsulphonylamino; and Q represents a heterocyclic radical selected from radicals of the formulae: <CHEM> whererin V represents hydrogen or methyl, <CHEM> wherein X represents halogen, methyl or methoxy and each of Y and Z, independently, represents cyano, nitro, methylaminocarbonyl, C1-4-alkylcarbonyl or C1-4-alkoxycarbonyl, the combination of these substituents being such that the dye has a magenta shade, and <CHEM> wherein R<7> represents C1-4-alkyl optionally substituted by halogen, cyano, C1-4-alkylcarbonyl or C1-4-alkoxycarbonyl, and n represents 0, 1 or 2.

We claim: 
     
       1. A thermal transfer printing sheet comprising a substrate having a coating comprising: (1) an anthraquinone dye of the formula: ##STR13##  wherein each of R 1  and R 2 , independently, represents hydrogen or C 1-4  -alkyl and rings A and B are optionally substituted in the free positions by non-ionic groups, and   (2) a monoazo dye of the formula: ##STR14##  wherein each of R 3  and R 4 , independently, represents C 1-4  -alkyl optionally substituted by halogen, cyano, phenyl, C 1-4  -alkoxy, C 1-4  -alkoxycarbonyl, C 1-4  -alkylcarbonyloxy, R 6  CONH--, R 6  NHCO--or R 6  NHCOO--in which R 6  represents C 1-4  -alkyl or optionally substituted aryl; R 5  represents hydrogen, halogen, C 1-4  -alkyl, C 1-4  -alkoxy, C 1-4  -alkylthio, beta-cyanoethyl, C 1-4  -alkylcarbonylamino or C 1-4  -alkylsulphonylamino; and   Q represents a heterocyclic radical selected from radicals of the formulae: ##STR15##  wherein V represents hydrogen or methyl, ##STR16##  wherein X represents halogen, methyl or methoxy and each of Y and Z, independently, represents cyano, nitro, methylaminocarbonyl, C 1-4  -alkylcarbonyl or C 1-4  -alkoxycarbonyl, the combination of these substituents being such that the dye has a magenta shade, and ##STR17##  wherein R 7  represents C 1-4  -alkyl optionally substituted by halogen, cyano, C 1-4  -alkylcarbonyl or C 1-4  -alkoxycarbonyl, and   n represents 0, 1 or 2, wherein the combination of said anthraquinone and said anonoazo dyes provides a magenta shade.     
     
     
       2. A thermal transfer printing sheet according to claim 1 wherein the coating also contains an anthraquinone dye of the formula: ##STR18## wherein R 8  represents C 5-12  -alkyl, R 9  represents H or C 1-4  -alkyl and rings E and F are optionally substituted in the free positions by non-ionic groups. 
     
     
       3. A thermal transfer printing sheet according to claim 1 wherein, in the dye of Formula I, R 1 , when C 1-4  -alkyl, is in the para position with respect to the link between rings B and D. 
     
     
       4. A thermal transfer printing sheet according to claim 1 wherein the dye of Formula I is 1-amino-4-hydroxy-2-phenoxy-anthraquinone. 
     
     
       5. A thermal transfer printing sheet according to claim 1 wherein, in the dye of Formula II, R 5  is hydrogen, chlorine, methyl or acetylamino. 
     
     
       6. A thermal transfer printing sheet according to claim 5 wherein Q is a radical of the formula: ##STR19## 
     
     
       7. A thermal transfer printing sheet according to claim 6 wherein the dye of Formula II has the structure: ##STR20## 
     
     
       8. A thermal transfer printing sheet according to claim 5 wherein Q is a radical of the formula: ##STR21## wherein R 7  is as defined in claim 1. 
     
     
       9. A thermal transfer printing sheet according to claim 1 wherein the dyes of Formula I and Formula II are employed in such proportions that the mixture contains from 5 to 40% of the dye of Formula II on a weight basis. 
     
     
       10. A thermal transfer printing sheet according to claim 9 wherein the mixture contains from 10 to 30% of the dye of Formula II on a weight basis. 
     
     
       11. A thermal transfer printing sheet according to claim 10 wherein the mixture contains from 15 to 25% of the dye of Formula II on a weight basis. 
     
     
       12. A thermal transfer printing process which comprises contacting a transfer sheet according to claim 1, with a receiver sheet, so that the dye is in contact with the receiver sheet and selectively heating areas of the transfer sheet whereby dye in the heated areas of the transfer sheet is selectively transferred to the receiver sheet.